Paper-feeding mechanism for photographic printers

ABSTRACT

This is an invention which permits precise feeding of a readily adjustable predetermined length of paper progressively in a stepby-step intermittent manner through a photographic printer. This is accomplished by a precisely variable length actuating arm intermittently rotatable through a predetermined constant arc (such as one complete revolution) and connected to a paperfeeding roll assembly for intermittent feeding of the paper through the printer.

United States Patent 1111 3,610,499

[72] Inventor Albert F. Gallistel 1,023,883 4/1912 Scott 226/157Wayzata, Minn. 2,779,590 1 1957 Seastrom 226/141 x [21] Appl. No.831,049 3,172,592 3/1965 Norden 226/157 :iled d Jo 5 3 9 7 FOREIGNPATENTS atente ct. Assignee Pako Corporation 1,246,392 1 1/1959 France226/139 Minneapolis, Minn. Primary Examiner-Allen N. Knowles AssistantExaminer-Gene A. Church Attarney.lohn W. Adams [54] PAPER-FEEDINGMECHANISM FOR PHOTOGRAPl-IIC PRINTERS 2 Claims, 4 Drawing Figs.

{52] US. Cl 226/115,

226/157, 226/195 ABSTRACT: This is an invention which permits precisefeed- [51] lnLCl B65h 17/04 ing f a read), adjustable predetermined l hf paper Fleld of Search 226/8, 120, progressively i a te b teintermittent manner through a 175 photographic printer. This isaccomplished by a precisely vari- [56] References Cited able lengthactuating arm intermittently rotatable through a predetermined constantarc (such as one complete revolu- UNITED STATES PATENTS tion) andconnected to a paper-feeding roll assembly for inter- 2,841,997 7/1958Maust 226/139 X mittent feeding of the paper through the printer.

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sum 2 nr 2 )lnWW 1 PAPER-FEEDING MECHANISM FOR PHOTGGRAPIIIC PRINTERS Inthe past, feeding devices for photographic printers have been relativelydifficult to adjust for feeding an infinite range of different sizeprints through the printer and for the most part have not beensufficiently accurate to prevent substantial waste of the printingpaper.

The principal object of the present invention is to provide a preciselyand easily adjustable step-by-step intermittent drive for the feedingroll assembly which will feed an infinite range of extremely accurateincremental lengths of the printing paper through the printer thussubstantially eliminating waste and designed to produce relatively slowstarting and stopping feeding speeds which are gradually accelerated toa maximum speed and gradually decelerated therefrom.

This object and others will more fully appear from the followingdescription made in connection with the accompanying drawing whereinlike reference characters refer to similar parts throughout the severalviews, and in which:

FIG. 1 is a diagrammatic rear elevational view of a supply and takeupmechanism for a photographic printer including my controllablyadjustable feeding mechanism;

FIG. 2 is a somewhat more detailed rear view of the feeding mechanism,per se;

FIG. 3 is a top plan view of the structure shown in FIG. 2 and as viewedsubstantially from the line 3-3 of FIG. 2; and,

FIG. 4 is an enlarged view of the control arm, per so, as viewedsubstantially from the line 4-4 of FIG. 3 with the arm rotatedapproximately 90 from its starting position.

FIG. 1 shows diagrammatically the paper supply, feeding and takeupmechanisms for intermittently feeding precisely predetermined lengths ofphotographic paper through a printer. A supply roll or magazine carriesthe supply of paper to be fed through the printer. A supply mechanism 11 of conventional construction (details not shown) is provided forwithdrawing lengths of paper from the roll 10 and providing a slack loop120 in the web of paper 12 as it passes to the feeding rolls 13 and 14.An identifying number stamp mechanism 15 of conventional design numberseach print as the paper is fed through the printer. Tensioning rolls l6and 17 are slightly larger in diameter than rolls 13 and 14 to maintaina predetermined desired tension on the paper while the same is disposedin the exposure area A during the printing process. A takeup roll 18 isprovided with a suitable takeup mechanism 19 of conventional design(details not shown).

,The feeding rolls 13 and 14 and tensioning rolls l6 and 17 arepositively driven as by a chain and sprocket drive. The chain isdesignated by the numeral 20 and is trained about a pair of sprockets14a and 170 respectively attached in fixed relation to the driving rolls14 and 15, and the rolls l3 and 17 are driven from rolls 14 and 15 as bysets of meshed gears.

The chain 20 is provided with a return spring 21 connected with one endthereof. The other end of the chain is connected with an actuating arm22 having an adjusting slide 23 mounted I for adjustable slidingmovement longitudinally of said arm. An

elongated worm 24 is journaled for rotation on said arm and suitablemeans for producing rotation thereof is provided such as the bevel gears25 and a rotatable control knob 26. The slide 23 is meshed with the worm24 so that rotation of the worm will produce longitudinal shiftingmovement of the slide back and forth along the length of the arm 22. Theslide is pivotally connected with the chain 20 as by the pivot pin 23aand controls the effective length of the actuating arm 22. The arm isprovided with a numbered scale to indicated the amount of paper fedthrough the feeding rollers and tensioning rollers for each rotation ofthe arm. A pointer 23b is provided on the slide to facilitate accuratereading of the numbered scale as best shown in FIG. 4.

i I In the form shown the arm 22 is rotated through a complete circle bya single revolution type clutch mechanism 27 to which power is suppliedfrom an electric motor 28. In the mechanism illustrated an endless chainand sprocket drive 29 connects the output shaft of the motor 28 with theclutch 27 and drive shaft 30 which is keyed to the arm 22 as best shownin FIG. 4.

A single revolution type clutch 27 has a latch or stopping pawl 32 whichpositively engages the shoulder on the stop roller 33 as best shown inFIG. 2. A solenoid 34 is provided to release the pawl 32 from theshoulder at the beginning of each revolution of the arm 22. Anantibacklash-overrunning clutch mechanism 34a is also provided on shaft30 to prevent backlash movement of the shaft at the end ofeachrevolution as best shown in FIG. 3. An overrunning clutch mechanism34 is also provided at the end of each of the rollers 14 and 17 whichprevents reverse rotation of each of said rollers during the returnportion of the actuating stroke of the chain 20.

The starting position of the arm 22 is vertical and an idler sprocket 31is provided directly above the axis 30 of the arm 22. At the beginningof the rotational movement of the arm 22 the increment of movement ofthe chain will be at a minimum for each degree of rotational arc of thearm. The speed of the chain will accelerate gradually to its maximumspeed at a point when the arm reaches the horizontal position at the endof the first quarter of the complete revolution and this isapproximately its position as viewed in FIG. 4. The speed of the chainwill gradually diminish for the next of arc. The chain 20 will then bereturned by the spring 21 to its starting position under the control ofthe arm 22. The overrunning clutches 35 permit return of the chainwithout reversing the rollers 14 and 17. The rate of acceleration anddeceleration of the chain 20 will be at a minimum at the beginning andend of the actuating stroke and also at the beginning and end of thereturn stroke. This imparts a smoother driving action to the chainduring each actuation thereof. A pair of stepped-guiding rollers 32 and33 disposed outside of the rollers 13, 14 and 16 and I7 respectivelyprovide guiding shoulders for engaging the edges of the paper 12 andkeep the same centered as is passes through the exposure area A. Thesteps correspond to the various standard width papers conventionallyused for photographic print paper.

A conventional control circuit (not shown) is provided to expose thepaper after each revolution of the arm 22 and after each such exposurethe am is again actuated.

Occasionally it is necessary to run a series of test prints and insteadof using full lengths of paper for such a test which would be verywasteful, it is desirable to provide a short stroke paper feed by whichonly a short length of paper will be exposed for test purposes. Oneinstance where such a series of test prints would be used is when a newbatch of paper is being put into the printer. The paper manufacturercannot maintain absolute consistency of the emulsion on the print paperfrom batch to batch and therefore when a new batch is to be used theoperator will run a series of test prints with prescribed testvariations in the print exposure conditions in order to obtain anoptimum setting for that particular emulsion. Such a short stroke paperfeed could be provided by a solenoid 36 connected to a stirrup 37 whichsurrounds a portion of the lower run of the chain 20 as best shown inFIGS. 1 and 2. When the solenoid 36 is actuated this stirrup will pulldown on the chain and cause only a short increment of paper to beadvanced. A return spring 36a returns the stirrup to its normal positionwherein the chain 20 will pass freely back and forth therethrough uponnormal operation of the arm feeding mechanism as described. The exposurearea A is reduced in size for the test runs as by opaque slides (notshown) movable into and out of the area A.

It will be seen that I have provided a relatively simple yet highlyeffective method and apparatus for precisely varying the intermittentstep-by-step feeding of photographic paper from a supply roller into theexposure area A from which it is ultimately discharged.

It will, of course, be understood that various changes may be made inthe form, details, arrangement, and proportion of the parts withoutdeparting. from the scope of the invention, which generally stated,consists in the matter set forth in the accompanying claims.

What is claimed is:

l. in a photographic printer of the type having paper supply mechanismand a takeup mechanism with an exposure area receiving photographicprinting paper to be exposed;

an adjustable paper-feeding mechanism comprising a pair of feedingrollers having driving engagement with said paper,

a driving mechanism including an actuating arm having positive drivingconnection with at least one of said feeding rollers,

power means for rotating said arm through a predetermined are,

means for precisely varying the effective length of said actuating am tocontrollably vary the amount of rotation of said feeding rollersproduced by said arm when the same is rotated through said predeterminedare to precisely control the length of paper fed into the exposure areaby said feeding rollers,

means for maintaining the desired predetermined tension in said paperwhile the same is in said exposure area, and

a short feed mechanism connected with said feeding rollers for rotatingthe same through an are substantially less than the are produced by saidactuating arm.

2. in a photographic printer of the type having paper supply mechanismand a takeup mechanism with an exposure area receiving photographicprinting paper to be exposed;

an adjustable paper-feeding mechanism comprising a pair of feedingrollers having driving engagement with said paper,

a driving mechanism including an actuating arm having positive-drivingconnection with at least one of said feeding rollers,

power means for rotating said arm through a predetermined are,

means for precisely varying the effective length of said actuating armto controllably vary the amount of rotation of said feeding rollersproduced by said arm when the same is rotated through said predeterminedarc to precisely control the length of paper fed into the exposure areaby said feeding rollers,

means for maintaining the desired predetermined tension in said paperwhile the same is in said exposure area, and

said tension-maintaining means consisting in a pair of tensioningrollers of slightly greater diameter than said feeding rollers anddisposed on the opposite side of said exposure area from said feedingrollers and also having positive-driving connection with said arm andsaid paper to produce the same rotational speed as said feeding rollers.

1. In a photographic printer of the type having paper supply mechanismand a takeup mechanism with an exposure area receiving photographicprinting paper to be exposed; an adjustable paper-feeding mechanismcomprising a pair of feeding rollers having driving engagement with saidpaper, a driving mechanism including an actuating arm having positivedriving connection with at least one of said feeding rollers, powermeans for rotating said arm through a predetermined arc, means forprecisely varying the effective length of said actuating arm tocontrollably vary the amount of rotation of said feeding rollersproduced by said arm when the same is rotated through said predeterminedarc to precisely control the length of paper fed into the exposure areaby said feeding rollers, means for maintaining the desired predeterminedtension in said paper while the same is in said exposure area, and ashort feed mechanism connected with said feeding rollers for rotatingthe same through an arc substantially less than the arc produced by saidactuating arm.
 2. In a photographic printer of the type having papersupply mechanism and a takeup mechanism with an exposure area receivingphotographic printing paper to be exposed; an adjustable paper-feedingmechanism comprising a pair of feeding rollers having driving engagementwith said paper, a driving mechanism including an actuating arm havingpositive-driving connection with at least one of said feeding rollers,power means for rotating said arm through a predetermined arc, means forprecisely varying the effective length of said actuating arm tocontrollably vary the amount of rotation of said feeding rollersproduced by said arm when the same is rotated through said predeterminedarc to precisely control the length of paper fed into the exposure areaby said feeding rollers, means for maintaining the desired predeterminedtension in said paper while the same is in said exposure area, and saidtension-maintaining means consisting in a pair of tensioning rollers ofslightly greater diameter than said feeding rollers and disposed on theopposite side of said exposure area from said feeding rollers and alsohaving positive-driving connection with said arm and said paper toproduce the same rotational speed as said feeding rollers.